Tuberculin Skin Test

stidget99 · Jun 19, 2005

A positive TB test is an area of induration or firmness at the injection site that measures greater than 10mm in diameter.

Bird2 · Jun 19, 2005

I start nursing school in August and I had to get a number of immunizations and tests done to complete my health form. On Friday, I got the MMR, Polio, and Hep B vaccinations. I also had the TB skin test done. I have to go and get the test read tomorrow, but I am curious to know what a positive test looks like. The spot that was injected was itching and I scratched and now it's a small red circle on my arm. It's not a lump or anything, just a red spot where I scratched it. Is this considered positive?? What does it have to look like to be considered positive?? I'm freaking out because I don't have any other symptoms but I would hate to have to pay for an x-ray because of a false positive. The nurse who gave me the vaccinations mentioned something about the other vaccinations interfering with the TB test. Is this true??

Redness and itching is not a positive reaction. A lump (induration) is a positive reaction. If I had an employee react positive to a TB test I would first fill out a form that reviews and signs and symptoms of active disease. If they were positive but did not have night sweats, weight loss, cough etc then the Health Dept would more than likely not do anything except a chest x-ray. The Health Dept may even do the x-ray without charge.

shammy · Jun 19, 2005

Was it a 1 step or a 2 step?

I had an weird reaction to the 2nd step. Itching, and redness but NO wheel. The MD and NP that looked at it both decided that it was neg. I've since had 1 step tests be completely negative.

mojopsych · Jun 20, 2005

Was it a 1 step or a 2 step?
I had an weird reaction to the 2nd step. Itching, and redness but NO wheel. The MD and NP that looked at it both decided that it was neg. I've since had 1 step tests be completely negative.

I have no idea what step it was. Is it a prominent lump or just like raised skin??

MIA-RN1, RN · Jun 20, 2005

I start nursing school in August and I had to get a number of immunizations and tests done to complete my health form. On Friday, I got the MMR, Polio, and Hep B vaccinations. I also had the TB skin test done. I have to go and get the test read tomorrow, but I am curious to know what a positive test looks like. The spot that was injected was itching and I scratched and now it's a small red circle on my arm. It's not a lump or anything, just a red spot where I scratched it. Is this considered positive?? What does it have to look like to be considered positive?? I'm freaking out because I don't have any other symptoms but I would hate to have to pay for an x-ray because of a false positive. The nurse who gave me the vaccinations mentioned something about the other vaccinations interfering with the TB test. Is this true??

I had a big (about 1/2 dollar sized!) red itchy swollen area from mine, it was the kind w/ the four prongs (this was some time ago) Anyway, they told me it was positive and sent me for a chext Xray which was normal. From there to a pulmonologist who declared me normal too but they all seemed to feel I'd been xposed to TB. I took INH for a year and now I don't get any more TB tests but occasionally need Xrays for new employers, school etc.

I never had any symptoms of TB but DID have a wicked pneumonia about a year before the TB test came back goofy.

I would't worry about yours if its just red and not swollen. And if it is considered positive, unless you are actively sick, its a pain in the butt but bearable to deal with.

Bird2 · Jun 20, 2005

I have no idea what step it was. Is it a prominent lump or just like raised skin??

The first time you are given a TB test it is a 2 step. There after you receive a 1 step every year( this is called a booster). Basically the test is given and read 48-72 hours later. In a 2 step it is given again one week later and also read 48-72 hours later. When a TB test is read it is easy for the better to not look at the arm but just feel it. Your eyes can play tricks making think you feel a lump. Sometimes the indutation is very obvious other times it is barely there. If someone is a positive reactor they usually will not get another TB test but an employer will fill out a positve reactor form yearly and as needed to monitor for signs and symptoms of TB.

ANPFNPGNP · Aug 20, 2010

The first time you are given a TB test it is a 2 step. There after you receive a 1 step every year( this is called a booster). Basically the test is given and read 48-72 hours later. In a 2 step it is given again one week later and also read 48-72 hours later. When a TB test is read it is easy for the better to not look at the arm but just feel it. Your eyes can play tricks making think you feel a lump. Sometimes the indutation is very obvious other times it is barely there. If someone is a positive reactor they usually will not get another TB test but an employer will fill out a positve reactor form yearly and as needed to monitor for signs and symptoms of TB.

I'm a NP and I perform the majority of TB testing for nursing students in my area. I've had a few students tell me they've had positive results in the past and were required to have a chest x-ray (which turned out to be negative). NONE of those students had a positive TB skin test when I read it. They may have had indurations, but they weren't positive. Remember, there's specific criteria that determines if a test is positive or negative. You can find the information on the CDC website. For instance, if a person is HIV positive, then an induration (NOT REDNESS) of 5 mm or more is considered positive. If a patient is a recent immigrant (

Just a quick question. I'm charging $15 per test (includes reading) - I curious what other clinics are charging. Thanks for the infor! :nurse: